Objective To investigate whether alterations in the phosphorylation status of matrix metalloproteinase 2 (MMP-2) in the heart may be protective in the setting of ischaemia–reperfusion (IR) injury. Design In-vitro heart function and biochemical research study. Setting University basic science laboratory. Interventions Male Sprague–Dawley rats, weighing 250–350 g. Isolated rat hearts were perfused at constant pressure either aerobically for 75 min or subjected to 20 min of global, no-flow ischaemia followed by 30 min of reperfusion. Main Outcome Measures Heart mechanical function, MMP-2 activity and troponin I levels. Results The serine/threonine phosphatase inhibitor okadaic acid (OA) improved the recovery of mechanical function compared with control IR hearts and prevented the loss of troponin I. OA significantly reduced protein phosphatase 2A, but not protein phosphatase 1, activity in perfused hearts. IR stimulated the activation and release of MMP-2 into the coronary effluent in the first 2 min of reperfusion. This was accompanied by a decrease in the remaining activity and protein level of MMP-2 in heart tissue determined at the end of the reperfusion. OA did not alter the IR-stimulated release of MMP-2 into the coronary effluent, but reduced the decrease in MMP-2 in reperfused hearts. The immunoprecipitation of heart homogenates using anti-phosphoserine antibody showed that MMP-2 is phosphorylated. The dephosphorylation of MMP-2 by alkaline phosphatase treatment of homogenates prepared from IR hearts treated with OA significantly increased MMP-2 activity. Conclusions These results suggest that the phosphorylation status of MMP-2 is important in its contribution to myocardial IR injury.

Aims: Acute myocarditis is a potentially lethal inflammatory heart disease that frequently precedes the development of dilated cardiomyopathy and subsequent heart failure. At present, there is no effective standardized therapy for acute myocarditis, besides the optimal care of heart failure and arrhythmias in accordance with evidence-based guidelines and specific etiology-driven therapy for infectious myocarditis. Carvedilol has been shown to be cardioprotective by reducing cardiac pro-inflammatory cytokines present in oxidative stress in certain heart diseases. However, effects of carvedilol administration in acute myocarditis with its impact on matrix metalloproteinases’ (MMPs) activation have not been elucidated. Methods and Results: Carvedilol in 3 doses (2, 10, and 30 mg/kg) was given daily to 3 study groups of rats (n = 8) with experimental autoimmune myocarditis by gastric gavage for 3 weeks. In comparison to untreated rats (n = 8) with induced myocarditis, carvedilol significantly prevented the left ventricle enlargement and/or systolic dysfunction depending on the dose in study groups. Performed zymography showed enhanced MMP-2 activity in untreated rats, while carvedilol administration reduced alterations. This was accompanied by prevention of troponin I release and myofilaments degradation in cardiac muscle tissue. Additionally, severe inflammatory cell infiltration was detected in the nontreated group. Carvedilol in all doses tested, had no impact on severity of inflammation. The severity of inflammation did not differ between study groups and in relation to the untreated group. Conclusions: The protective effects of carvedilol on heart function observed in the acute phase of experimental autoimmune myocarditis seem to be associated with its ability to decrease MMP-2 activity and subsequently prevent degradation of myofilaments and release of troponin I while not related to suppression of inflammation.

Matrix metalloproteinase 2 (MMP-2) is activated in hearts upon ischemia-reperfusion (IR) injury and cleaves sarcomeric proteins. It was shown that carvedilol and nebivolol reduced the activity of different MMPs. Hence, we hypothesized that they could reduce MMPs activation in myocytes, and therefore, protect against cardiac contractile dysfunction related with IR injury. Isolated rat hearts were subjected to either control aerobic perfusion or IR injury: 25 min of aerobic perfusion, followed by 20 min global, no-flow ischemia, and reperfusion for 30 min. The effects of carvedilol, nebivolol, or metoprolol were evaluated in hearts subjected to IR injury. Cardiac mechanical function and MMP-2 activity in the heart homogenates and coronary effluent were assessed along with troponin I content in the former. Only carvedilol improved the recovery of mechanical function at the end of reperfusion compared to IR injury hearts. IR injury induced the activation and release of MMP-2 into the coronary effluent during reperfusion. MMP-2 activity in the coronary effluent increased in the IR injury group and this was prevented by carvedilol. Troponin I levels decreased by 73% in IR hearts and this was abolished by carvedilol. Conclusions: These data suggest that the cardioprotective effect of carvedilol in myocardial IR injury may be mediated by inhibiting MMP-2 activation.

Background: Acute myocarditis often progresses to heart failure because there is no effective, etiology-targeted therapy of this disease. Simvastatin has been shown to be cardioprotective by decreasing matrix metalloproteinases’ (MMPs) activity. The study was designed to determine whether simvastatin inhibits MMPs activity, decreases the severity of inflammation and contractile dysfunction of the heart in experimental autoimmune myocarditis (EAM). Methods: Simvastatin (3 or 30 mg/kg/day) was given to experimental rats with EAM by gastric gavage for 21 days. Then transthoracic echocardiography was performed, MMPs activity and troponin I level were determined and tissue samples were assessed under a light and transmission electron microscope. Results: Hearts treated with simvastatin did not show left ventricular enlargement. As a result of EAM, there was an enhanced activation of MMP-9, which was significantly reduced in the high-dose simvastatin group compared to the low-dose group. It was accompanied by prevention of myofilaments degradation and reduction of severity of inflammation. Conclusions: The cardioprotective effects of simvastatin in the acute phase of EAM are, at least in part, due to its ability to decrease MMP-9 activity and subsequent decline in myofilaments degradation and suppression of inflammation. These effects were achieved in doses equivalent to therapeutic doses in humans.

This narrative review provides an overview of scientific studies on dietary supplements that may affect circulating testosterone (T) levels to explore which substances are scientifically proven to increase T concentration. We also review the scientific literature for their potential mechanisms and laboratory test changes triggered by their use. Based on the analysis of existing data on substances used to increase endogenous T levels, especially double-blind placebo-controlled randomized clinical trials, we selected 2 herbal extracts with the best documented positive effects on T levels, Withania somnifera root and root extracts/leaves and seed extracts of Trigonella foenum-graecum. Although these substances have different postulated mechanisms of action, both significantly increase T levels in men. Withania somnifera may inhibit the effects of cortisol and prolactin on the hypothalamic-pituitary-gonadal axis and directly affect the hypothalamus. Trigonella foenum-graecum seeds contain the active substance diosgenin, which is a precursor for sex hormone synthesis in gonads.